JP2008002755A - Microwave oven - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability of a weight sensor and to improve reliability of a microwave oven by applying a structure for preventing water or oil flowing from a tray from flowing to a substrate of the weight sensor through a load transmitting shaft. <P>SOLUTION: This microwave oven has the weight sensor comprising the load transmitting shaft 32 receiving the load of the tray 40, a flanged cap 50 disposed on the load transmitting shaft, a falling edge portion disposed at the circumference of a flange portion of the flanged cap, a top plate covering a substrate portion disposed at a lower part of the load transmitting shaft and having a hole for inserting the load transmitting shaft, and a rising edge portion formed at the circumference of the hole of the top plate and rising inside of the falling edge portion disposed on the flange portion of the flanged cap. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a microwave oven having a weight sensor.

  2. Description of the Related Art Conventionally, a microwave oven provided with a weight sensor is disclosed in Patent Document 1.

JP-A-01-134121

  In a microwave oven equipped with a weight sensor, the weight sensor receives a load from a mounting table or a saucer (hereinafter referred to as a saucer or the like) on which an object to be heated is placed and measures the load. They are connected by a transmission shaft.

  For this reason, when cooked juice or oil overflows the saucer etc., it flows through the outside of the saucer etc. and flows under the saucer etc., and is transmitted to the load transmission shaft located in the lower part of the heating chamber to detect the load with the weight sensor May flow onto the substrate. When juice or oil flows into the substrate, there is a possibility of causing a malfunction of the circuit or degrading an element provided on the substrate.

  Then, an object of this invention is to provide the microwave oven provided with the structure where the juice and oil from a saucer etc. do not flow directly into the board | substrate of a weight sensor.

  In the present invention, in order to prevent the juice or oil overflowing from the saucer from flowing along the load transmission shaft, the load transmission shaft is provided with a ridge having a downward outer periphery, and the upper surface plate covering the weight sensor substrate portion is provided. Has a rising part that rises inside a downward-facing ridge.

  According to the present invention, the juice or oil that flows from the tray does not flow through the load transmission shaft and flows into the substrate of the weight sensor, so that the reliability of the weight sensor can be improved and the reliability of the microwave oven can be improved.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  The main body of the microwave oven shown in FIG. 1 is provided with a door 2 having a handle 1 on the front surface thereof. The door 2 has a transparent glass window 3 so that the inside state can be seen. By pulling the handle 1 forward, the door 2 can be opened to a horizontal position by a hinge mechanism (not shown) with its lower part as a fulcrum. A gap 10 is provided between the main body lower portion 9 and the door 2 in a state where the door 2 is closed in order to open and close the door 2.

  An operation panel 4 is provided on the lower side of the door 2, and a display device 5 made of liquid crystal with a white background is provided at the center thereof. Menu displays 6 are provided on both sides of the display device 5.

  In the conventional menu display, the background color is generally black, and the characters are printed on the glass window 3 in a color that is easy to see with respect to black. For this reason, the types of colors that can be used for characters were limited. In the present embodiment, a substrate on which a light emitting element such as an LED is mounted is arranged on the back side of the glass window 3, and this serves as a backlight so that the menu display 6 can be seen more clearly. Therefore, there is no limitation on the color used for characters.

  Further, the operation panel 4 and the display device 5 are separated, and the display device 5 is arranged on the glass window 3 side which is information of the operation panel 4 so that the line of sight with the user is closer. It is easy to use.

  The operation time is set by rotating a dial 4a provided on the operation panel 4. Therefore, the operation time can be set quickly.

  In order to cool a substrate (not shown) provided in the door 2 for the operation panel 4, the display device 5 and the menu display 6, a structure through which the outside air passes through the door 2 is provided. The air flow entering from the air inlet 7 provided at the bottom of the door 2 cools the substrate provided in the door 2 and is discharged from the air outlet 8 provided below the handle 1. Since the air inlet 7 is at the bottom of the door 2 and the air outlet 8 is at the almost uppermost part of the door 2, air is circulated by natural convection, and both the air inlet 7 and the air outlet 8 are on the lower side. Because it is located, it is in a position where it is difficult to see directly, and the appearance is also good.

  A plurality of ventilation openings 12 are provided on the side surface of the outer frame 11. Ventilation ports 12 are also provided on the opposite side surface and rear side. If it is a position where water does not enter directly from the upper surface, the position and the number of the vent holes 12 are arbitrary, and the temperature can be reduced as the number increases.

  FIG. 2 is a front view of the microwave oven according to the present embodiment as viewed from the bottom surface without the outer frame 11 of the microwave oven. The electric component cooling fan 20 is disposed on the lower surface on the right side of the rear surface.

  Most of the cooling air by the electric component cooling fan 20 passes through the air passage of the ventilation A, cools the electrical components of the inverter board 22 on which the high voltage transformer 21 is mounted, and separates it into the ventilation B and the ventilation C to separate the power supply board. 23 is cooled.

Ventilation C is exhausted to the outside from the side, and ventilation B passes through the inside of the power supply board 23, reaches the weight sensor 24b, and is exhausted from the ventilation port 12 on the side.

  Since the position of the weight sensor 24b is far from the electric component cooling fan 20, the cooling efficiency is very poor. For this reason, temperature becomes high compared with two other weight sensors. Although the weight sensor 24a is under the power supply board 23, since it is cooled by the ventilation B, the distance from the electrical component cooling fan 20 is also short and the cooling efficiency is relatively good.

  Further, the cooling air flow D by the cooling fan 20 for electric parts is cooled by efficiently applying the cooling air by the weight sensor 24 c by the ventilation guide 25.

The weight sensor 24 c is fixed to the internal bottom plate 31 via the weight sensor top plate 30 by means of a mounting screw 26. An antenna drive motor 27 for driving an antenna (not shown) for diffusing high-frequency electromagnetic waves from the magnetron 29 is disposed at the center.

The magnetron cooling fan 28 is disposed on the lower surface on the left side of the back surface opposite to the electric component cooling fan 20. Ventilation E by the magnetron cooling fan 28 cools the magnetron 29 and most of the air is exhausted to the outside through the ventilation port 12 from the side surface.

  In the conventional weight sensor 24 shown in FIG. 3, the load transmission shaft 32 is fixed by the weight sensor upper surface plate 30 and the substrate mounting plate 33.

  On the upper surface of the weight sensor upper surface plate 30, there is a burring 34 facing upward. The flinger 35 is press-fitted into the load transmission shaft 32, and the liquid dripping from the upper surface is caused to flow outside the burring 34 so as not to contact the substrate 36 directly.

  Since the material of the flinger 35 requires heat resistance and flexibility, a sheet material of fluorine or silicon resin is used. For this reason, material cost becomes high and the shape is a single shape. In the case of a molded product, there is a problem that the processing cost further increases.

  The weight sensor detection unit 37 receives the load of the load transmission shaft 32, is converted into a signal that can be read by the microcomputer by the substrate 35, and is input to the microcomputer.

A plurality of attachment holes 38 are formed in the weight sensor upper surface plate 30, and are attached to the inner bottom plate 31 by attachment screws 26.

  FIG. 4 shows a part of the load transmission shaft 32 of the weight sensor 24 in the conventional example. A saucer 40 on which a cooking device is placed is in contact with the upper surface of the load transmission shaft 32, and the weight is transmitted to the weight sensor detection unit 37 via the load transmission shaft 32.

  The upper surface portion of the load transmission shaft 32 uses an expensive PPS (polyphenylene sulfide) having high heat resistance because the temperature in the chamber reaches 250 to 300 ° C.

  In addition, when the juice or oil from the cooking object in the warehouse flows from the load transmission shaft 32, the flinger 35 and the burring 34 prevent the juice or oil from entering the substrate 36 side. However, since the shape of the flinger 35 is a simple shape, it has been found that if the amount of juice or oil increases, the flinger 35 is easily transmitted to the back surface and enters.

  Therefore, in the weight sensor 24 in one embodiment of the present invention shown in FIG. 5, the load transmission shaft 32 is covered with a hooked cap 50, and the load transmission shaft 32 is provided on the weight sensor top plate 30. A flange portion 52 of the flanged cap 50 is provided so as to be positioned on the outer peripheral side of the burring 34 that is a rising portion rising from the periphery of the hole and to overlap the burring 34 in the radial direction. The flange portion 52 includes a first flange portion that expands in the radial direction and a second flange portion that is connected to the outer periphery of the first flange portion and extends downward in the axial direction.

For this reason, a large amount of juice or oil that has entered from the bottom plate 31 of the cabinet flows reliably to the outside of the burring 34 by the flange 52 and does not enter the substrate 36. As long as the relationship between the flanged cap 50 and the load transmission shaft 32 is fixed, it may be in a state where there is no gap as in press-fitting or in a state where there is a gap.

  The flanged cap 50 is positioned at the lower limit at the first step 51. The axial length of the first stage is L2> L1, where L2 is the distance from the upper surface to the tip of the flanged cap 50 and L1 is the distance to the bottom plate 31 in the cabinet. Thereby, even if the flanged cap 50 and the load transmission shaft 32 are loosely fixed, they are not detached from the load transmission shaft 32 when pulled up to the upper surface.

  Moreover, since the flanged cap 50 directly touches the atmosphere in which the temperature in the cabinet is 250 to 300 ° C., it is preferable to use PPS having high heat resistance.

  The tip temperature of the load transmission shaft 32 is increased to about 100 to 150 ° C. because the thermal gradient of the tip of the load transmission shaft 32 is increased by the flanged cap 50 and the cooling air flows between the bottom plate 31 and the weight sensor top plate 30. Decreases. Therefore, the flanged cap 50 can also use a resin having a low heat-resistant temperature. Therefore, a material such as PBT (polybutylene terephthalate), which is planned for PPS and has a low material cost, can be used.

  Further, since the flanged cap 50 can be manufactured by molding, a complicated shape is possible, and the material used can be reduced. When the same material as the load transmission shaft 32 is used, the machining cost can be reduced by using the same material.

FIG. 6 is a circuit block diagram of a microwave oven in one embodiment of the present invention. The power source 60 is a commercial power source of AC 100V, 50/60 Hz. When the power switch 61 is turned on, a current flows through the circuit. The filter circuit 63 cuts power line noise and airwave noise to the magnetron 62.

  The alternating current is converted into direct current by the rectifier circuit 64 and supplied to the inverter circuit 65. The inverter circuit 65 increases the frequency and supplies it to the magnetron driving circuit 66. In the magnetron driving circuit 66, a high frequency is applied to the primary side of a high voltage transformer (not shown), and a high voltage is generated on the secondary side to operate the magnetron 62.

  A signal from the operation panel 4 is input to the microcomputer 68, and the operation result is controlled by the microcomputer 68 and displayed on the display circuit 67.

  The weight sensor 24 is provided in a total of three places, two on the front side and one on the rear side. Thus, the weight of the object to be heated is detected through the dish placed on the weight sensor 24, and the detection result is input to the microcomputer 68.

  A temperature sensor 70 for detecting the internal temperature and a buzzer circuit 71 for notifying the end of cooking and the above are also connected to the microcomputer 68.

  A drive circuit 72 is connected to the microcomputer 68, and the electronic component cooling fan 73, the magnetron cooling fan 74, the upper heater 75 provided on the upper surface inside the cabinet, and the temporary surface inside the cabinet via the drive circuit 72. A hot air motor 77 or a hot air unit for driving a fan for blowing air provided in a hot air unit (not shown) for jetting a high-temperature air flow provided in the chamber with the lower heater 76 separated from the back wall of the chamber. A hot air heater 78 for heating the air sucked in and a boiler heater 79 provided in a steam generator (not shown) for supplying steam into the hot air unit are connected to each other. Control.

  Since the surface of the heat insulation sheet 24 is also about 93 ° C., an aluminum foil 25 for preventing radiation is further attached. For the aluminum foil 25 that is directly facing the substrate, an aluminum foil 25 with an insulating coating is used. As a result, the gap between the substrate and the aluminum foil for preventing radiation is about several millimeters, but by performing insulation treatment, short circuit due to insufficient insulation distance due to variations in the height of the solder surface and electronic component mounting legs can be prevented. Can do. The temperature reduction effect by the aluminum foil is about 7 ° C. per sheet.

  As described above, according to the embodiment of the present invention, the load transmission shaft that receives the load of the tray, the flanged cap provided on the load transmission shaft, and the falling provided around the flange portion of the flanged cap And a top plate having a hole through which the load transmission shaft passes, covering the substrate portion provided below the load transmission shaft, and a fall provided on the flange portion of the hooked cap provided around the hole of the upper surface plate Since it has a weight sensor provided with the rising part which stands | starts up inside a part, a microwave oven provided with the structure where juice and oil do not flow into the board | substrate of a weight sensor can be provided.

It is a perspective view of a microwave oven in one example of the present invention. It is the front view seen from the bottom face of the microwave oven shown in Drawing 1 in the state where an outer frame was removed. It is a figure which shows the weight sensor in a prior art example. It is a partial detail drawing of the load transmission shaft of the weight sensor of a prior art example. FIG. 5 is a partial detail view of a load transmission shaft of a weight sensor according to an embodiment of the present invention. It is a circuit block diagram of a microwave oven concerning one example of the present invention.

Explanation of symbols

24 ... Weight sensor, 30 ... Weight sensor top plate, 31 ... Inside bottom plate, 32 ... Load transmission shaft,
34 ... burring, 40 ... saucer, 50 ... cap with hook.

Claims (5)

  A load transmission shaft that transmits the load of the table on which the food is placed, a first flange that is provided on the load transmission shaft and that extends in the radial direction, and a second flange that extends downwardly by connecting to the outer periphery of the first flange And an upper surface plate provided with a rising portion that rises inside the second flange portion around a hole through which the load transmission shaft passes, and a load transmitted from the load transmission shaft below the upper surface plate. A microwave oven having a weight sensor provided with a substrate provided with an electronic circuit for converting into a signal.   The microwave oven according to claim 1, comprising a plurality of the weight sensors.   The microwave oven according to claim 1, wherein the first flange portion and the second flange portion are provided in a cap portion provided between the load transmission shaft and the base.   The microwave oven according to claim 3, wherein the load transmission shaft and the cap portion are made of a resin material, and a heat resistant temperature of the resin material of the load transmission shaft is lower than a heat resistant temperature of the resin material of the cap portion.   5. The microwave oven according to claim 3, wherein the first brim part and the second brim part are provided below a bottom plate in a heating chamber in which the platform is arranged.

Images